This invention relates to video to digital data recording systems and in particular to the direct, real time digital data recording of thermal energy.
The majority of the existing and proposed digitization methods for detecting and recording thermal energy fall into three catagories: calibrated film recording; analog magnetic tape recording; and, direct digital recording. Calibrated film recording systems include an infrared camera and display, a display camera for providing calibrated photographs of the display, a microdensitometer for processing the photographs and a digital tape recorder for recording the densitometer output. Analog magnetic tape recording system include an infrared camera, conditioning electronics, an analog tape recorder, a general purpose digitization facility and a digital tape recorder. The direct digital recording system requires only the infrared camera, an analog/digital converter, a computer and the digital tape recorder.
The first two, methods require an intermediate analog storage mechanism and post-experiment digitization at non-real-time rates. The film recording method has the advantages of simplicity and economy for those laboratories with ready access to a microdensitometer. However, in many respects this is the least desirable of the three alternatives owing to the inherent non-linearity and low information density of photographic film or plates. Magnetic analog tape recording systems eliminate these problems, but still require two separate steps to produce a computer compatible digital tape. Direct digital recording systems in the past, have been less than satisfactory due to the data speed handling limitation of digital tape recording devices. State-of-the-art digital tape recorders are incapable of handling the high speed data bursts that are digitized during camera active scan periods. This limitation precludes their direct use for direct real time recording. The use of a computer as a buffer to achieve real time recording has resulted in the further limitation of having to operate some system components at less than full capacity.
The present invention is directed toward providing a direct real time digital recording system that overcomes these limitations.